Our study suggests that (i) the severity of pre-existing secondary hyperparathyroidism is the main factor determining its persistence after renal transplantation, (ii) persistent secondary hyperparathyroidism is characterized by an autonomous pattern of PTH secretion, (iii) the VDR BB genotype seems to be related to lower PTH levels.

peritoneal fluid makes a reduction of phosphate dietary Phosphate metabolism in chronic renal failure intake impractical, the protein content of the diet being strictly linked to that of phosphate. Even though hypophosphataemia has been reportedWeekly phosphate removal in CAPD has been occasionally in chronic renal failure patients on dialysis reported to be ~70 mmol, with 4×2 l exchanges per treatment [1,2], phosphate (Pi) retention, often associday [12]. This value is quite similar to that found in ated with increased serum Pi, is the most common 35 of our CAPD patients (65.5±40.6 mmol/week), finding in this clinical setting. Pi retention is secondary and is ~20 mmol per week less than in haemodialysis to reduced or null renal excretion, and dialysis removal (HD) (84.3±19.1 mmol/week). However, in our is often, but not always, insufficient as compared with CAPD patients, urinary excretion (48.8±21.4) suba variably reduced intestinal absorption of Pi [3][4][5].stantially contributes to Pi balance, representing ~40% The main metabolic consequences of phosphate of the total Pi removed, while in most HD patients retention have been related to: (i) a possible direct [6 ] this route of Pi excretion is negligible. We found that and indirect (mediated by calcium and calcitriol reducurinary Pi excretion was linearly related to glomerular tion) [7,8] stimulation of parathyroid hormone; (ii) a filtration rate (GFR) values, evaluated as the mean direct involvement in extraosseous calcifications [9]; of creatinine and urea clearances in our CAPD and (iii) a detrimental effect on renal function [10], that can still be maintained at a significant level in patients (uPi mmol/day=−1.11+1.39×GFR; r=0.91, continuous ambulatory peritoneal dialysis (CAPD) P<0.001), stressing the importance of the preservation patients.of residual renal function in maintaining a good Before addressing the problem of Pi removal by metabolic balance in CAPD. dialysis treatment, it might be useful to recall some When we considered the factors affecting the dialytic points on Pi body distribution. Of the more than 650 g removal of phosphate in our CAPD patients by means of Pi contained in a medium-sized man, ~85% is of a multiple regression analysis ( Table 1), we found contained in bone, 14% in the cells and only 1% or that plasma Pi concentration plays the main role. less is in the plasma. It is also important to bear in Another important factor is represented by the glucose mind that the bulk of intracellular Pi is represented by concentration in the dialysate, and its influence on organic phosphate (nucleoside phosphate compounds, Pi removal was independent of ultrafiltration rate. phosphorylated enzymes, 2,3-diphosphoglycerate, pho-Finally, Pi removal by peritoneal dialysis was greatly sphocreatine, etc.) at 10-100 times the concentration affected by dialysate volume, with a calculated removal of inorganic phosphate with which it is in equilibrium. of ~95 mmol/week at a dialysate volume of 12 l per The inorganic intracellular phosphate is in turn...

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SummaryThis 5 year observational multicentre study conducted in the Nord Italian Transplant programme area evaluated outcomes in patients receiving kidneys from donors over 60 years allocated according to a combined clinical and histological algorithm. Low-risk donors 60-69 years without risk factors were allocated to single kidney transplant (LR-SKT) based on clinical criteria. Biopsy was performed in donors over 70 years or 60-69 years with risk factors, allocated to Single (HR-SKT) or Dual kidney transplant (HR-DKT) according to the severity of histological damage. Forty HR-DKTs, 41 HR-SKTs and 234 LR-SKTs were evaluated. Baseline differences generally reflected stratification and allocation criteria. Patient and graft (death censored) survival were 90% and 92% for HR-DKT, 85% and 89% for HR-SKT, 88% and 87% for LR-SKT. The algorithm appeared userfriendly in daily practice and was safe and efficient, as demonstrated by satisfactory outcomes in all groups at 5 years. Clinical criteria performed well in low-risk donors. The excellent outcomes observed in DKTs call for fine-tuning of cut-off scores for allocation to DKT or SKT in high-risk patients.

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